Initial contact shapes the perception of friction

Humans efficiently estimate the grip force necessary to lift a variety of objects, including slippery ones. The regulation of grip force starts with the initial contact and takes into account the surface properties, such as friction. This estimation of the frictional strength has been shown to depend critically on cutaneous information. However, the physical and perceptual mechanism that provides such early tactile information remains elusive. In this study, we developed a friction-modulation apparatus to elucidate the effects of the frictional properties of objects during initial contact. We found a correlation between participants’ conscious perception of friction and radial strain patterns of skin deformation. The results provide insights into the tactile cues made available by contact mechanics to the sensorimotor regulation of grip, as well as to the conscious perception of the frictional properties of an object.

Initial contact shapes the perception of friction

Humans efficiently estimate the grip force necessary to lift a variety of objects, including slippery ones. The regulation of grip force starts with the initial contact, and takes into account the surface properties, such as friction. This estimation of the frictional strength has been shown to depend critically on cutaneous information. However, the physical and perceptual mechanism that provides such early tactile information remains elusive. In this study, we developed a friction-modulation apparatus to elucidate the effects of the frictional properties of objects during initial contact. We found a correlation between participants' conscious perception of friction and radial strain patterns of skin deformation. The results provide insights into the tactile cues made available by contact mechanics to the sensorimotor regulation of grip, as well as to the conscious perception of the frictional properties of an object.

Decoding of EEG Signals Shows No Evidence of a Neural Signature for Subitizing in Sequential Numerosity

Numerosity perception is largely governed by two mechanisms. The first so-called subitizing system allows one to enumerate a small number of items (up to three or four) without error. The second system allows only an approximate estimation of larger numerosities. Here, we investigate the neural bases of the two systems using sequentially presented numerosity. Sequential numerosity (i.e., the number of events presented over time) starts as a subitizable set but may eventually transition into a larger numerosity in the approximate estimation range, thus offering a unique opportunity to investigate the neural signature of that transition point, or subitizing boundary. If sequential numerosity is encoded by two distinct perceptual mechanisms (i.e., for subitizing and approximate estimation), neural representations of the sequentially presented items crossing the subitizing boundary should be sharply distinguishable. In contrast, if sequential numerosity is encoded by a single perceptual mechanism for all numerosities and subitizing is achieved through an external postperceptual mechanism, no such differences in the neural representations should indicate the subitizing boundary. Using the high temporal resolution of the EEG technique incorporating a multivariate decoding analysis, we found results consistent with the latter hypothesis: No sharp representational distinctions were observed between items across the subitizing boundary, which is in contrast with the behavioral pattern of subitizing. The results support a single perceptual mechanism encoding sequential numerosities, whereas subitizing may be supported by a postperceptual attentional mechanism operating at a later processing stage.

Is the Illusion of Authenticity Beneficial? Merely Perceiving Decisions as Guided by the True Self Enhances Decision Satisfaction

Many people endorse a “true-self-as-guide” (TSAG) lay theory of decision-making that suggests following one’s true self is an optimal strategy for making decisions. Across five studies ( N = 1,320), we test whether perceived use of the true self enhances decision satisfaction. Study 1 provides correlational evidence. Studies 2 and 3 provide experimental evidence that participants felt more satisfied with choices made under TSAG instructions, compared to alternate strategies. Critically, we argue that perceived use of the true self enhances decision satisfaction regardless of whether consulting the true self actually influences the decision made. Studies 4 and 5 find evidence in support of this perceptual mechanism. This research provides insight into one way by which people find satisfaction amid life’s uncertainty, extending existing research on the role of the concept of true selves in positive functioning.

Verbal aggression in modern poetry: conventional and uncon­ventional functioning of discourse markers

The article examines the specifics of speech aggression in poetic communication. Special attention is paid to the unconventional functioning of discourse markers of aggression. The aim of the study is to analyse aggressive verbal behaviour in poetic communication and iden­tify distinctive characteristics of expressing aggression in everyday discourse. The research methodology includes methods of linguopragmatic, linguopoetic and discourse analyses. The author studies discourse markers of verbal aggression in poetic speech acts, where aggression can be expressed explicitly and implicitly. The study reveals specific strategies of expressing verbal aggression in poetic communication, which can include the self-referential criticism (through verbal aggression directed at the language of the poetic utterance, the actor of utter­ance, the poetic utterance as such and also the perceptual mechanism). The author studies the formation of aggressive message in poetic discourse and its subjectification.

Scleral pigmentation leads to conspicuous, not cryptic, eye morphology in chimpanzees

Gaze following has been argued to be uniquely human, facilitated by our depigmented, white sclera [M. Tomasello, B. Hare, H. Lehmann, J. Call, J. Hum. Evol. 52, 314–320 (2007)]—the pale area around the colored iris—and to underpin human-specific behaviors such as language. Today, we know that great apes show diverse patterns of scleral coloration [J. A. Mayhew, J. C. Gómez, Am. J. Primatol. 77, 869–877 (2015); J. O. Perea García, T. Grenzner, G. Hešková, P. Mitkidis, Commun. Integr. Biol. 10, e1264545 (2016)]. We compare scleral coloration and its relative contrast with the iris in bonobos, chimpanzees, and humans. Like humans, bonobos’ sclerae are lighter relative to the color of their irises; chimpanzee sclerae are darker than their irises. The relative contrast between the sclera and iris in all 3 species is comparable, suggesting a perceptual mechanism to explain recent evidence that nonhuman great apes also rely on gaze as a social cue.

Experimental Investigation of Perceptual Characteristics of Functional Cemented Backfilling Materials in Coal Mines

For investigating perceptual stress characteristics of Functional Cemented Backfilling Materials (FCBM) in coal mines, we prepared functional specimens based on Cemented Backfilling Materials (CBM) with the perceptual stress ability, and clarified their conductive mechanism, perceptual mechanism, and possible engineering applications. Using mechanical tests and the network parallel dynamic method, the mechanical and electrical properties of the prepared materials and the perceptual characteristics under mechanical–electric coupling conditions were analyzed in depth. The test results demonstrate that the deformation of FCBMs obey standard stress–strain rules, while the conductive phase addition can deteriorate their mechanical properties and simultaneously enhance the electrical conductivity of materials. Through fitting, the percolation threshold was determined to be 9.85%. Before the failure, the spatial distribution of the apparent resistivity in the materials was shown to follow the X-shaped radial pattern; after the failure, the material apparent resistivity obeys different distribution rules at various stages. The apparent resistivity of FCBM is negatively correlated with the strain value at the elastic and plastic stages and positively correlated with it at the failure stage. When the graphite content exceeds the percolation threshold, the materials exhibit a favorable perceptual functionality at the elastic stage.

Biological motion as an innate perceptual mechanism driving social affiliation

Collective behavior, such as shoaling in teleost fish, is driven by the perceptual recognition of conspecific animals. Because social interactions are mutual, it has been difficult to disentangle the exact sensory cues that trigger affiliation in the first place from those that are emitted by receptive and responsive shoal mates. Here we overcome this challenge in a virtual reality assay in zebrafish. We discovered that simple visual features of conspecific biological motion provide an irresistible shoaling cue. Individual juvenile fish interact with circular black dots projected onto a screen, to the same extent as they do with real conspecifics, provided these virtual objects mimic the characteristic kinetics of zebrafish swim bouts. Other naturalistic cues previously implicated in shoaling, such as fish-like shape, pigmentation pattern, or non-visual sensory modalities are not required. During growth, the animals’ stimulus preferences shift gradually, matching self-like kinetics, even in fish raised in isolation. Virtual group interactions and our multi-agent model implementation of this perceptual mechanism demonstrate sufficiency of kinetic cues to drive assortative shoaling, a phenomenon commonly observed in field studies. Coordinated behavior can emerge from autonomous interactions, such as collective odor avoidance in Drosophila, or from reciprocal interactions, such as the codified turn-taking in wren duet singing. We found that individual zebrafish shoal autonomously without evidence for a reciprocal choreography. Our results reveal individual-level, innate perceptual rules of engagement in mutual affiliation and provide experimental access to the neural mechanisms of social recognition. (239/250 words max)Significance StatementSocial affiliation is ubiquitous in the animal kingdom, but fundamental sensory cues driving group formation remain elusive. During swarm behavior, for example, individuals dynamically exchange sensory cues with their neighbors, presenting an intertwined choreography opaque to formal analysis of causal stimulus-response relationships. Using a virtual interaction assay for psychophysical analysis, we solved this issue and identify biological motion as the irresistible trigger of social affiliation in zebrafish, Danio rerio. Given that many species form groups including shoals, flocks and herds, perceptual mechanisms of social recognition and their underlying neural circuits are likely shared across vertebrates. The identification of fundamental affiliation-inducing cues is a prerequisite for relating individual-level sensory-motor transformations to collective behavior. (112/120 words max)